Weightlifting systems are well known. Typically weightlifting systems include a bar with removable plates of varying weights. A weightlifter may adjust the weights by adding plates to the bar or removing plates from the bar.
In Canada, most plate sets prior to about 1970 were graduated in pounds. A changeover to metrics occurred in the early 70s due to an increased international exposure of weightlifting as well as Canada's anticipated metrification. In addition, the Russian “World Record” plate set was popular at this time and was only available in metric. The conversion to metrics occurred over a transitional period. In Olympic weightlifting oriented gyms, 45, 35, 25, 10, 5, and 2.5 pound plates; 5 pound collars; and 45 pound bars were gradually replaced with 20, 15, 10, 5, 2.5, and 1.25 kilo plates; 2.5 kilo collars; and 20 kilo bars.
The French produced the first rubber plate set in the early sixties. The first time rubber plates were used in Canada was around 1967. Rubber plates came about because they were more floor friendly. As weightlifting records increased, manufacturers found less room for plates on their bar sleeves. One solution was to decrease the width of each plate. However, this made the pressure-per-area even greater when forming plates. A rubber-iron combination plate was invented that was narrower than the old iron plates but wider and softer than the new ones. However, they were also more expensive and had a shorter life.
The size of the heaviest discs is typically 450 mm. Fifteen kilogram plates have only been full sized (diameter) since the 1960s. The Russian “World Record” plate sets had them first. Larger plates also spread the impact on more barbell surface area. There are now full-sized 10 pound plates, even some 5 and 2.5 pound plates. Twenty-five kilogram plates were also added in 1972. Four years later 50 kilogram rubber plates were added.
The barbell has not changed fundamentally since the 1928 Olympics where the revolving sleeve barbell became the standard. Attempts at standardizing the bar were made as early as around 1905, but standardization could not be finalized until the lifts were finally standardized in 1928. Only a few superficial changes have been instituted since then, such as the markings. A women's bar was added in 1996, with colors that distinguish men's bar from a women's bar in 2000.
During a number of years, it was common to use barbells without collars, whether in training or competition. This was possible due to the tight fit. The rules were changed in 1972 to require collars, where a standard two clamps were used to grip the sleeve and a revolving screw device was used to tighten the sleeve against the plates. The device worked but it was also awkward to use. So at the 1958 Brussels Worlds Fair, the Soviets introduced to the world their revolutionary new “World Record” barbell set. Its plates were made of steel instead of cast iron. The plates also were edge trimmed with chrome or stainless steel while their sides were painted blue. This made for very photogenic competition shots. The sleeves had a series of grooves that allowed a ratchet clip on the collar to catch and secure the collar into position. Slippage was then impossible, while a screw device without the usual levers could make the finer adjustments against the plates. This set remained popular until 1972. The collar system never did catch on due to the wider sleeves that were necessary. As a result, 50 mm sleeves became standard. The Soviets were somehow allowed to use a rubber version in the 1980 Olympics that was still outside the rules. In the 1972 Olympics, a barbell was used, which reverted to essentially exercise collars. These had a single screw lever that wound against the sleeve. The screw lever was very simple but fine adjustments to secure the plates were not possible.
There exists weightlifting plates that are not used for competition but are instead used for training. These types of plates are referred to hereinafter as technique plates. FIG. 1 is a diagram of conventional technique plates 10. The technique plates 10 shown are each 10 pounds and each has a 17½ inch diameter. These technique plates 10 are used for weightlifting training but are problematic because they bend. Consequently, a weightlifter cannot repeat a stable setup for lifting the weights from the floor, which is not good for learning weightlifting technique.
FIG. 2 is a diagram of other conventional technique plates 20. These technique plates 20 are made thin in order to achieve a light weight and low mass for weightlifting training. These technique plates 20 are hexagonal shaped to enable them to stand up. However, these technique plates 20 cannot be dropped, which is not good for learning weightlifting technique.
Another type of training plate used for weightlifting is called a bumper plate (not shown). As the name suggests, bumper plates have a rubber composition. The rubber helps to dampen the impact when the plate is dropped.
Bumper plates are greater than 10 kg in weight, out of the technique range, and are dropped with more force and made to couple on the bar with comparable heavy weights.
Accordingly, what is needed is an improved technique plates for training. The present invention addresses such a need.